The present invention relates to actuators, including but not limited to those used on turbochargers for automotive engines.
One key component of a turbocharger for an automotive engine is the actuator. As part of a closed loop control system, the actuator senses the pressure in the turbocharger and responds accordingly by varying the position of the turbocharger. The position of the waste gate valve, in turn, controls the turbocharger pressure sensed by the actuator. Although various known turbocharger actuators are available, many of them are plagued with a hysteresis problem. Hysteresis is the result of internal friction within the actuator. Consequently, the response of the actuator in one direction may be slower or markedly different than in the other direction. For actuators having a piston assembly comprising a piston mounted on an actuator rod, the piston assembly sometimes sticks or drags when attempting to move along the wall of the actuator housing.
Therefore, there is a need for a turbocharger actuator which exhibits low hysteresis during its operation. Thus, a primary objective of the present invention is the provision of an actuator with improved hysteresis characteristics.
A further objective of the present invention is the provision of an actuator having a piston with a plurality of grooves thereon for respectively receiving O-rings, the O-rings and the grooves being proportioned such that the O-rings are movable axially within the grooves.
A further objective of the present invention is the provision of a method for reducing hysteresis in a turbocharger actuator.
A further objective of the present invention is the provision of an actuator which is economical to produce, durable and reliable in use, and smoothly operable.
These and other objectives will become apparent from the drawings, as well as from the description and claims which follow.